This application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2004-248772 filed in Japan on Aug. 27, 2004, the entire contents of which are hereby incorporated by reference.
The present invention relates to electrophotographic image forming apparatuses such as copying machines, facsimile machines, and printers.
In this type of image forming apparatus, an image is formed on a surface of a sheet while the sheet is being conveyed, and if an abnormality such as a jam occurs during the conveying of the sheet, the conveying of the sheet is stopped and an operation is conveyed out to solve the jam or other abnormality. Ordinarily, the conveying of the sheet is stopped at the same time as the abnormality occurs, or the conveying of the sheet is stopped after the sheet is conveyed to a location where the sheet can be removed from the image forming apparatus easily.
For example, a technique is disclosed in JP 2003-307981A in which, when an abnormality such as a jam occurs, the sheet is conveyed to a position between a transfer belt and a fixing device, after which the conveying of the sheet is stopped, thereby making it easy to remove the sheet from the transfer belt.
Furthermore, a technique is disclosed in JP H06-186810A in which, although the conveying of the sheet is stopped when an abnormality such as a jam occurs, manual conveying of the sheet to the fixing device is enabled so that the image on the surface of the sheet can be fixed.
In this regard, sometimes an abnormality such as a jam may occur to a sheet on which an image of a developer has been transferred such that the conveying of the sheet is stopped prior to the sheet being conveyed to the fixing device. In this case, when the sheet is removed from the image forming apparatus, the image of the developer on the surface of the sheet is not fixed, and therefore problems have occurred such as the developer on the surface of the sheet spattering and smearing the surrounding area, or the user's hand becoming soiled.
Alternatively, a portion of the sheet may be in a state of insertion with respect to the fixing device when the conveying of the sheet is stopped. In this case, a problem is caused in that the developer on the surface of the sheet smears the fixing device. Fixing devices commonly sandwich the sheet between a heating roller and a pressure roller, and fix the image of the developer to the surface of the sheet by applying heat and pressure to the image of the developer on the surface of the sheet. When the conveying of the sheet is stopped in a state in which a portion of the sheet is inserted into the fixing device and the sheet is sandwiched between the heating roller and the pressure roller, the developer on the surface of the sheet sometimes becomes thermally fused such that the developer adheres to the heating roller or the pressure roller, leading to smearing and abrasions on the surface of the rollers, and the rollers may become damaged. Moreover, when the conveying of sheets recommences after the jam or other abnormality has been cleared, smearing on the rollers may be transferred to a sheet that is newly conveyed in.